1. Field of the Ivention
This invention concerns a stripping device for hard surfaces including hardwoods such as Eucalypts and plastics such as epoxy and polyester resins. A particular application of the device lies in stripping gelcoat together with marine paint layers or cured weatherproof coatings from structures made from glass reinforced plastics (GRP). Marine vessels occupy this category.
Whereas portable buildings made of GRP degrade through exposure to ultraviolet, some GRP boats suffer gradual water permeability which is aggravated in seawater by osmosis. The Gel-Coat skin of the boat ceases to exclude water and eventually a costly hull restoration or replacement becomes necessary.
Likewise swimming pools made of GRP may suffer both ultraviolet degradation and water permeability.
2. Description of Prior Art
Known methods of restoration depend on rubbing away the Gel-Coat with coarse grit abrasive discs or wheels carried by an angle grinder. This operation fills the surrounding air with dust which may contain toxic anti-fouling paints and other hazardous compounds. The person operating the grinder must therefore wear full protective clothing, headgear, eyeshields and breathe filtered air in order to be safe. These precautions preserve only the operator. Toxic or irritant dust may still reach other workers. The dust is still free to penetrate the moving parts of the grinder.
Operators are hampered by such protective aids. The efficiency of abrasion is poor, even using the best discs and wheels but more serious is the difficulty in ensuring that a uniform reduction in thickness is occurring as the job proceeds. Additionally parts of a boat hull have compund curvatures which makes the area accessible to a disc face quite small. Rates of removal are low, typically 2 square meters/hr and the operation is consequently expensive.
Sandblasting leaves a lumpy finish and likewise results in air pollution.
The purpose of the stripping operation is to remove permeable GRP to a depth sufficient to ensure that the new GRP and/or epoxy paint applied on top will constitute an impermeable barrier to seawater.